Such a molding lines, e.g., the floor space of a motor vehicle. Its lower finished contour is adapted to the contour of the floor panel as well as to the built-in parts (ventilation, cables, etc.) of the vehicle. Its upper finished contour is covered, e.g., with a carpet. The molding compensates the differences in the shapes of the floor panel and the carpet. In addition, it is used for sound insulation and heat insulation. Cotton and synthetic fibers and flakes or a mixture thereof may be used as the material for the molding. A certain binding of this material already takes place during the introduction of the material into the mold, because the fibers or flakes get more or less entangled. Thermoplastic binders are added for the permanent dimensional stabilization of the bond.
A device for preparing such moldings is described in DE-GM 93 12 868. Moldings which have equal density throughout despite differences in the wall thickness are to be prepared with this device. The material is applied for this purpose by means of a program-controlled die head to different areas of the mold in different layer thicknesses. An air flow generated by a vacuum source compacts the material applied.
The more complicated the shape of the different mold contours and the narrower the spaces in the mold, the smaller must be the die to reproduce the contours of the mold at least essentially. The smaller the die head, the longer it takes to apply the material. Furthermore, this type of introduction of the material involves the risk that the material will be deposited in a stratified form. The cause of this is the vacuum acting continuously on the material, which aligns the fiber components in parallel to the surface of the mold. After its preparation, such a molding tends to readily undergo delamination under certain circumstances, i.e., to pull apart layer by layer. In addition, it is difficult to prepare moldings with steep changes in contour, because only more or less flat piles of material are always formed by the die head, and these piles will no longer permit differences in thickness at closely spaced locations at equal density, and they are deformed in the finishing mold such that zones with different densities will be formed in an undesirable manner.
A process for preparing fiber moldings is described in WO 91/18828 A1. Fibers with thermoplastic binders are used in this case as well. A filling chamber is filled with the premixed material by means of vacuum, after which hot air flows through the filling chamber. The chamber is subsequently closed to the final material thickness and compacted. The material in the filling chamber is cooled in the next process step, and then removed. The shape of the filling chamber itself does not change in this process. This means that local differences in density in the finished part can be avoided after the pressing process to a limited extent only, because only the differences in the thickness of the molding in the filling chamber become noticeable during the deposition of the material. However, these differences in thickness are not sufficient to specifically influence the density of the material.